package org.glvnsjc.webapp.taglib;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.jsp.tagext.TagData;
import javax.servlet.jsp.tagext.TagExtraInfo;
import javax.servlet.jsp.tagext.VariableInfo;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.glvnsjc.Constants;

/**
 * Implementation of <code>TagExtraInfo</code> for the <b>constants</b>
 * tag, identifying the scripting object(s) to be made visible.
 *
 * @author Matt Raible
 */
public class ConstantsTei
    extends TagExtraInfo
{
    private final Log log = LogFactory.getLog( ConstantsTei.class );

    /**
     * Return information about the scripting variables to be created.
     * @param data the input data
     * @return VariableInfo array of variable information
     */
    public VariableInfo[] getVariableInfo( TagData data )
    {
        // loop through and expose all attributes
        List<VariableInfo> vars = new ArrayList<VariableInfo>();

        try
        {
            String clazz = data.getAttributeString( "className" );

            if ( clazz == null )
            {
                clazz = Constants.class.getName();
            }

            Class c = Class.forName( clazz );

            // if no var specified, get all
            if ( data.getAttributeString( "var" ) == null )
            {
                Field[] fields = c.getDeclaredFields();

                AccessibleObject.setAccessible( fields, true );

                for ( Field field : fields )
                {
                    String type = field.getType().getName();
                    vars.add( new VariableInfo( field.getName(), ( ( field.getType().isArray() ) ? type
                        .substring( 2, type.length() - 1 )
                        + "[]" : type ), true, VariableInfo.AT_END ) );
                }
            }
            else
            {
                String var = data.getAttributeString( "var" );
                String type = c.getField( var ).getType().getName();
                vars.add( new VariableInfo( c.getField( var ).getName(),
                                            ( ( c.getField( var ).getType().isArray() ) ? type.substring( 2, type
                                                .length() - 1 )
                                                + "[]" : type ), true, VariableInfo.AT_END ) );
            }
        }
        catch ( Exception cnf )
        {
            log.error( cnf.getMessage() );
            cnf.printStackTrace();
        }

        return vars.toArray( new VariableInfo[] {} );
    }
}
